Non-Point Sources (NPS) PoUution Modelling and Water Quality Improvement Using Wetland

Sustainability of water quality for urban ecosystem is a great concern in Malaysia
nowadays. Recent studies demonstrate significant increase in river pollution in part
contributed by non-point sources pollution which occurs when an area becomes
urbanized. The objectives of this project are to (a) determine the water quality
originating from Sungai Darnansara catchment, (b) predict the performance of
wetland as a stormwater treatment measure in protecting the receiving waters by
using model simulation, and (c) compare the results from the predicted model against
results from a laboratory-scale wetland. The method used in solving this problem is
based on computer modelling with input data collected from the field. The model
used in this project is the Model for Urban Stormwater Improvement
Conceptualisation (MUSIC), which was developed by Cooperative Research Centre
for Catchment Hydrology (CRC-CH) in Australia. The scope of the simulation study
is to predict the pollution loads of Total Suspended Solid (TSS), Total Nitrogen (TN)
and Total Phosphorus (TP) and also the pollutants reduction using wetland in Sungai
Darnansara catchment. Based on the data collected and water quality modeling, the
downstream part of the catchment can be classified as Class IV. According to DOE
and DID data, the Water Quality Index for the same part was also Class IV, which
proved that this model can also be used in tropical countries. In order to achieve a
Water Quality Objective (WQO) of Class II, water quality improvement by
intervening wetlands was predicted and the percentage reduction was determined. A
laboratory-scale wetland was constructed and tested in the laboratory. The results of
pollutants reduction by the laboratory-scale wetland were compared with the result
obtained from the computer model. The results from both systems were found to be
comparable. TSS, TP and TN were reduced by 51.7%, 51.4% and 51.4% in MUSIC
and by 56.9%, 43.6% and 44.3% in the laboratory respectively. The difference
between the two systems is less than I 0%. The outcome of this project is expected to
be able to overcome the water quality issues arising from urban ecosystem.